This application is a continuation of International Patent Application No. PCT/US2013/042280, filed on May 22, 2013, which claims the benefit of U.S. Provisional Application No. 61/650,403, filed on May 22, 2012, which are all incorporated by reference herein.
Injuries to the atlanto-axial junction (e.g. odontoid fractures, transverse ligament injuries) are common occurrences, affecting approximately up to 50,000 individuals each year in the United States. Surgical intervention is frequently necessary to prevent atlanto-axial subluxation with concomitant spinal cord injury. To prevent post-injury displacement, spinal fusion (arthrodesis) is performed to fuse the 1st and 2nd cervical vertebrae and thus stabilize the affected area.
Many fixation devices for stabilizing the atlantoaxial junction are configured to completely prevent relative motion. However, arthrodesis limits rotation of the upper cervical spine and head, which can negatively impact an individual's participation in simple activities of daily living. In addition, spinal arthrodesis has been found to increase loading stress at adjacent segments with a potential for acceleration of rates of degeneration.